National Train Day is coming May 7th from 11a.m. to 4p.m. Union Station will be transformed into the an annual mob scene where geeky train enthusiasts elbow little Thomas the Tank Engine-lovers to celebrate all things locomotive.

The crowds are thick and the lines are long. But the payoff is good for any kid who gets wide-eyed at the sound of a whistle. Metro-ing is definitely recommended for this free event.

This year, highlights will include:

• Train Equipment Displays

• Model Train Displays

• An Amtrak birthday party to celebrate the line’s 40th anniversary. with magicians, arts and crafts and giveaways throughout the day.

If you’re not sure what to expect, check out some highlights from last year.